Digital audio data compression has become an important technique in the audio industry. New formats have been introduced that allow high quality audio reproduction without the need for the high data bandwidth that would be required using traditional techniques. AC-3 and more recently Enhanced AC-3 (E-AC-3) coding technology has been adopted by the Advanced Television Systems Committee (ATSC) as the audio service standard for High Definition Television (HDTV) in the United States. E-AC-3 has also found applications in consumer media (digital video disc) and direct satellite broadcast. E-AC-3 is an example of perceptual coding, and provides for coding multiple channels of digital audio to a bitstream of coded audio and metadata.
There is interest in efficiently decoding a coded audio bit stream. For example, the battery life of portable devices is mainly limited by the energy consumption of its main processing unit. The energy consumption of a processing unit is closely related to the computational complexity of its tasks. Hence, reducing the average computational complexity of a portable audio processing system should extend the battery life of such a system.
The term x86 is commonly understood by those having skill in the art to refer to a family of processor instruction set architectures whose origins trace back to the Intel 8086 processor. As result of the ubiquity of the x86 instructions set architecture, there also is interest in efficiently decoding a coded audio bit stream on a processor or processing system that has an x86 instruction set architecture. Many decoder implementations are general in nature, while others are specifically designed for embedded processors. New processors, such as AMD's Geode and the new Intel Atom are examples of 32-bit and 64-bit designs that use the x86 instruction set and that are being used in small portable devices.